Well, until recently even F1 race could be consisted to consist of several 'sprint races'- and I guess a 'quick change' battery systems could be easily developed instead of refuelling. Say, battery pack with quick release mechanism in car's floor that gets dropped when the car is raised for tyre change and new one is wheeled in and installed immediately...

F1 EV's might work with a series of shorter "heat races". Similar to what speedway bike racing uses.

As for the notion of "amazing" advancements in EV battery technology, these advancements should be weighed against those of recip IC engines. In terms of cost, efficiency, reliability, etc. modern recip IC engines are still keeping ahead of their battery-electric competition.

Dude, I have my story straight. Do I have to explain you 1st grade mathematics and what average means?

Okay here we go with an example:Little Johnny loves eggs and eats them every day. Monday he eats 3, tuesday he eats 1, wednesday he eats 7, thursday the eggs are empty and he eats none, triday he eats 4 saturday he eats 2 and sunday he eats 2 again. How many eggs does little Johnny eat average a day?

First we add up how many eggs Johnny eats total:

3+ 1+ 7+ 0+ 4+ 2+ 2____ 19

So Johnny eats a total of 19 eggs in a week and we know that a week has 7 days.Now we divide the number of eggs eaten by little Johnny by the number of days a week has:

19:7=2,714.....

So Johnny eats an average of 2,71something eggs a day.

Do you understand now the concept of math and average or do I have to explain it a third time?

For everybody else who has a proplem with my numbers, just believe me, I know wtf I talk about.

Back on topic: there was a proposal for a battery swap system in Israel. I think that was under development with Renault and meant for the Renault Fluence.I remember seeing something about it on TV some time ago. It was supposed to be a fully automatic swap station. Does anybody know details about it?

What about flywheel storage systems? Surely they could be charged more quickly and last longer?

Porsche uses flywheel technology in their GT3 hybrid. IIRC that flywheel is good for a short boost of <10 seconds.How big must such a device be to be able to store a decent amout of energy? The one in the 911 is about the size of a big suitcase.

In order to get something useful you have to build a big and also heavy device...you want to stick into a formula race car...?

What about flywheel storage systems? Surely they could be charged more quickly and last longer?

Any system that recharges by moving energy alone (eg electricity or mechanical work) across the system boundary will suffer to some extent from the following limitation. Say you have an energy storage device with enough capacity to deliver an average 200 kW for one hour. If wish to recharge that device in one minute, the charge rate will need to be 60 x 200 = 12,000 kW (plus perhaps 20% or more for charge/discharge ineffficiencies). To recharge in 6 seconds would require 120,000 kW (160,000 hp) - not easy to do, even mechanically via a shaft (assuming you have a source which is capable of that sort of power output.) You would probably need a "pit flywheel" which has been charging for the last hour while the car was out.

Note. Conventional refuelling involves moving matter (fuel) across the system boundary. This equates to a very high "recharge" rate due to the energy density of hydrocarbon fuels. One litre (quart) per second is equivalent to about 8,000 kW after allowing for IC engine conversion efficiency.

Any system that recharges by moving energy alone (eg electricity or mechanical work) across the system boundary will suffer to some extent from the following limitation. Say you have an energy storage device with enough capacity to deliver an average 200 kW for one hour. If wish to recharge that device in one minute, the charge rate will need to be 60 x 200 = 12,000 kW (plus perhaps 20% or more for charge/discharge ineffficiencies). To recharge in 6 seconds would require 120,000 kW (160,000 hp) - not easy to do, even mechanically via a shaft (assuming you have a source which is capable of that sort of power output.) You would probably need a "pit flywheel" which has been charging for the last hour while the car was out.

Note. Conventional refuelling involves moving matter (fuel) across the system boundary. This equates to a very high "recharge" rate due to the energy density of hydrocarbon fuels. One litre (quart) per second is equivalent to about 8,000 kW after allowing for IC engine conversion efficiency.

Understood.

In the case of batteries the higher charge rates reduce the life of the batteries. Does partial charging and discharging also reduce the life of batteries?

Also, Greg's point about the enegry density of flywheels is understood. How does it compare to the best batteries today?

"Does partial charging and discharging also reduce the life of batteries?"

It doesn't much affect lead acids or NiMh or LiPo. Famously it hammers NiCd. I can't remember with AgZn, but that is not a practical chemistry. I don't know about other chemistries

http://scholar.sun.a...e/10019.1/17864 for flywheels, seems to suggest 400 Wh/kg based on 30 seconds of reading, roughly the same as a lithium primary cell, or 4 times that of a LiPo rechargeable cell.

witnessing that bloody thing accelerate trough the Nurburgring 24h pitlane and turn on the IC engine only at the end of it, was one of stranger experiences I had.. Marvelous car, should have won on it's maiden outing, had it not been for a IC engine failure..

http://scholar.sun.a...e/10019.1/17864 for flywheels, seems to suggest 400 Wh/kg based on 30 seconds of reading, roughly the same as a lithium primary cell, or 4 times that of a LiPo rechargeable cell.

So a flywheel could have the same energy density as the best batteries?

Well it would be a bit heavy. Those were intended to be zero maintenance, basically helicopter in the entire solar cell and flywheel power module, wire it up to the repeater, and never look at the thing again for 20 years. They'd have used steel flywheels. A lighter one would need more maintenance, and would cost more - the 400 Wh/kg ones use a lot of carbon fibre.

One of the most interesting features is that engine power can be graduated by a track officer via remote.
This means you start with a very low powered kart and once you've shown ability to go under a certain time they increase your power.
Your allowed power settings are also registered on a database for future runs.
This avoids the need for "low power -harmless to all" karts that usually plague rental venues.
Even kids can go on the same karts as adults (of course in separate stints), via adjustable pedals and a very low power setting.

Agreed. FSAE is one example where the electric category is growing rapidly at the expense of IC. Performance in the electric category is on par and beginning to overtake IC eg the record in the acceleration test is now held by an electric car.

Innovation abounds. One team saved weight by adding AWD . Yep, adding drive to the front wheels massively increases the regen available (front axle typically does 70% of the braking) allowing a significant reduction in battery size.

Just what they have on the site: Kart has a differential (!) and front-rear brakes.

Sorry but I don't understand any italian and I didn't find anywhere a button to change the language.

...no more 0.06 liter of gasoline per lap, even with the factor 2.5 for the higher efficiency. 60 laps is 3.6 liters.

...your maths it works out at 9l over 60 laps.

Guys! It doesn't matter if we talk about 3.6 or 9 or maybe 15 litres over 60 laps. KERS in F1 is just an eyewash to make the people (that just fell out of a cows a...) believe they're now ecologically thinking.And even so: it is still a drop on a hot stone.

Your going off topic but in practical terms F1 teams got few limits from 2014 on their KERS system.

1Kw is not uncommon on RC car motors

they weight in at 170grams typically.

Similar figures leaves you with the motor alone at around 28kg.

Efficiency will likely go up with the size of the motor but since cooling becomes harder due to packaging im guessing the weight is not far of.

Since they will struggle with harvesting due to traction, batteries will be smaller but support higher burst.

Does anyone have a idea of the current motor weight?

So we can estimate more precise

Hold on now, 1 kW from an RC-motor is probably at around 60 - 80 kRpm, which is just not suitable for an F1 MGU and the 99% efficiency is also fantasy if you include all electrical transmission and battery power in and out.

But anyway, the paramount problem is still the batteries, how much do the state-of-the art 40 kWh Tesla S battery weigh?

200 kg for 40 kWh perhaps, which including 3 times higher efficiency equals 12.7 liters of gas, a few laps around a GP track?

That would most probably be a lead-acid battery Duc-Man, lithium-ion like in the Tesla is far more weight-efficient,
but 450 kg for the equivalent of some 15 liter of gas still makes it unsuitable for any serious racing activities.

Perhaps if they can improve the efficiency of induction transfer of electricity?

Say there were no rules just safety requirements, must be open wheel, must be electric (battery not hydrogen), everything else free (?). Could such a class work, would the cars be fast?

To return to the original question - yes, I think such a class would work and the cars would be fast and interesting. In the world of model aircraft and model cars electric motor/lipo batteried models are either equal to, or outperform IC versions of the same model. Electric types are also (obviously) much easier to start (dangerously easy in fact) and much more controllable in power output. I think Mats is the expert in this area - maybe be should comment. I personally can't see why the models could not be scaled up to full size and be just as effective.

However, I can't see in the forseeable future electric cars being successful on the road - basically because of the seemingly-impossible-to-solve length of time needed to "refuel"/recharge compared to IC cars.

To continue on this same theme - there are model electric motors of 3 horsepower that can be held in the palm of one hand. Back in my days in industry, a 3HP motor was 415 volts AC and was not able to be lifted by one person. Being pretty ignorant of "electrickery" - how can the model motors be so powerful for their size?

... To continue on this same theme - there are model electric motors of 3 horsepower that can be held in the palm of one hand. Back in my days in industry, a 3HP motor was 415 volts AC and was not able to be lifted by one person. Being pretty ignorant of "electrickery" - how can the model motors be so powerful for their size?

I suspect that the paramount reason is the brushless motors with 100 000 Rpm?